api: add function hook_url

9 files changed, 710 insertions, 57 deletions

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 0e8432748..0769999a4 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -72,6 +72,7 @@ set(LIB_CORE_SRC
   hook/wee-hook-process.c hook/wee-hook-process.h
   hook/wee-hook-signal.c hook/wee-hook-signal.h
   hook/wee-hook-timer.c hook/wee-hook-timer.h
+  hook/wee-hook-url.c hook/wee-hook-url.h
 )
 
 # Check for flock support
diff --git a/src/core/hook/wee-hook-process.c b/src/core/hook/wee-hook-process.c
index 4de66b131..ff676dffc 100644
--- a/src/core/hook/wee-hook-process.c
+++ b/src/core/hook/wee-hook-process.c
@@ -278,7 +278,9 @@ hook_process_child (struct t_hook *hook_process)
         {
             ptr_url++;
         }
-        rc = weeurl_download (ptr_url, HOOK_PROCESS(hook_process, options));
+        rc = weeurl_download (ptr_url,
+                              HOOK_PROCESS(hook_process, options),
+                              NULL);  /* output */
     }
     else if (strncmp (HOOK_PROCESS(hook_process, command), "func:", 5) == 0)
     {
diff --git a/src/core/hook/wee-hook-url.c b/src/core/hook/wee-hook-url.c
new file mode 100644
index 000000000..6f00da4f2
--- /dev/null
+++ b/src/core/hook/wee-hook-url.c
@@ -0,0 +1,419 @@
+/*
+ * wee-hook-url.c - WeeChat URL hook
+ *
+ * Copyright (C) 2023 Sébastien Helleu <flashcode@flashtux.org>
+ *
+ * This file is part of WeeChat, the extensible chat client.
+ *
+ * WeeChat is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * WeeChat is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with WeeChat.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <pthread.h>
+
+#include "../weechat.h"
+#include "../wee-hashtable.h"
+#include "../wee-hook.h"
+#include "../wee-infolist.h"
+#include "../wee-log.h"
+#include "../wee-string.h"
+#include "../wee-url.h"
+#include "../../gui/gui-chat.h"
+#include "../../plugins/plugin.h"
+
+
+/*
+ * Returns description of hook.
+ *
+ * Note: result must be freed after use.
+ */
+
+char *
+hook_url_get_description (struct t_hook *hook)
+{
+    char str_desc[1024];
+
+    snprintf (str_desc, sizeof (str_desc),
+              "URL: \"%s\", thread id: %d",
+              HOOK_URL(hook, url),
+              0);
+
+    return strdup (str_desc);
+}
+
+/*
+ * Displays keys and values of a hashtable.
+ */
+
+void
+hook_url_hashtable_map_cb (void *data, struct t_hashtable *hashtable,
+                           const void *key, const void *value)
+{
+    /* make C compiler happy */
+    (void) data;
+    (void) hashtable;
+
+    gui_chat_printf (NULL, "    %s: \"%s\"",
+                     (const char *)key,
+                     (const char *)value);
+}
+
+/*
+ * Runs callback of url hook.
+ */
+
+void
+hook_url_run_callback (struct t_hook *hook)
+{
+    if (url_debug)
+    {
+        gui_chat_printf (NULL, "Running hook_url callback for URL \"%s\":",
+                         HOOK_URL(hook, url));
+        gui_chat_printf (NULL, "  options:");
+        hashtable_map (HOOK_URL(hook, options), &hook_url_hashtable_map_cb, NULL);
+        gui_chat_printf (NULL, "  output:");
+        hashtable_map (HOOK_URL(hook, output), &hook_url_hashtable_map_cb, NULL);
+    }
+
+    (void) (HOOK_URL(hook, callback))
+        (hook->callback_pointer,
+         hook->callback_data,
+         HOOK_URL(hook, url),
+         HOOK_URL(hook, options),
+         HOOK_URL(hook, output));
+}
+
+/*
+ * Thread cleanup function: mark thread as not running any more.
+ */
+
+void
+hook_url_thread_cleanup (void *hook_pointer)
+{
+    struct t_hook *hook;
+
+    hook = (struct t_hook *)hook_pointer;
+
+    HOOK_URL(hook, thread_running) = 0;
+}
+
+/*
+ * URL transfer (in a separate thread).
+ */
+
+void *
+hook_url_transfer_thread (void *hook_pointer)
+{
+    struct t_hook *hook;
+
+    hook = (struct t_hook *)hook_pointer;
+
+    pthread_cleanup_push (&hook_url_thread_cleanup, hook);
+
+    (void) weeurl_download (HOOK_URL(hook, url),
+                            HOOK_URL(hook, options),
+                            HOOK_URL(hook, output));
+
+    pthread_cleanup_pop (1);
+
+    return NULL;
+}
+
+/*
+ * Checks if thread is still alive.
+ */
+
+int
+hook_url_timer_cb (const void *pointer, void *data, int remaining_calls)
+{
+    struct t_hook *hook;
+    const char *ptr_error;
+
+    /* make C compiler happy */
+    (void) data;
+    (void) remaining_calls;
+
+    hook = (struct t_hook *)pointer;
+
+    if (hook->deleted)
+        return WEECHAT_RC_OK;
+
+    if (!HOOK_URL(hook, thread_running))
+    {
+        hook_url_run_callback (hook);
+        ptr_error = hashtable_get (HOOK_URL(hook, output), "error");
+        if (ptr_error && ptr_error[0])
+        {
+            gui_chat_printf (
+                NULL,
+                _("%sURL transfer error: %s (URL: \"%s\")"),
+                gui_chat_prefix[GUI_CHAT_PREFIX_ERROR],
+                ptr_error,
+                HOOK_URL(hook, url));
+        }
+        unhook (hook);
+        return WEECHAT_RC_OK;
+    }
+
+    if (remaining_calls == 0)
+    {
+        hook_url_run_callback (hook);
+        if (weechat_debug_core >= 1)
+        {
+            gui_chat_printf (
+                NULL,
+                _("End of URL transfer '%s', timeout reached (%.1fs)"),
+                HOOK_URL(hook, url),
+                ((float)HOOK_URL(hook, timeout)) / 1000);
+        }
+        pthread_cancel (HOOK_URL(hook, thread_id));
+        usleep (1000);
+        unhook (hook);
+    }
+
+    return WEECHAT_RC_OK;
+}
+
+/*
+ * Starts transfer for an URL hook.
+ */
+
+void
+hook_url_transfer (struct t_hook *hook)
+{
+    int rc, timeout, max_calls;
+    long interval;
+
+    HOOK_URL(hook, thread_running) = 1;
+
+    /* create thread */
+    rc = pthread_create (&(HOOK_URL(hook, thread_id)), NULL,
+                         &hook_url_transfer_thread, hook);
+    if (rc != 0)
+    {
+        gui_chat_printf (NULL,
+                         _("%sError running thread in hook_url: %s (URL: \"%s\")"),
+                         gui_chat_prefix[GUI_CHAT_PREFIX_ERROR],
+                         strerror (rc),
+                         HOOK_URL(hook, url));
+        unhook (hook);
+        return;
+    }
+
+    /* main thread */
+    timeout = HOOK_URL(hook, timeout);
+    interval = 100;
+    max_calls = 0;
+    if (timeout > 0)
+    {
+        if (timeout <= 100)
+        {
+            interval = timeout;
+            max_calls = 1;
+        }
+        else
+        {
+            interval = 100;
+            max_calls = timeout / 100;
+            if (timeout % 100 == 0)
+                max_calls++;
+        }
+    }
+    HOOK_URL(hook, hook_timer) = hook_timer (hook->plugin,
+                                             interval, 0, max_calls,
+                                             &hook_url_timer_cb,
+                                             hook,
+                                             NULL);
+}
+
+/*
+ * Hooks a URL.
+ *
+ * Returns pointer to new hook, NULL if error.
+ */
+
+struct t_hook *
+hook_url (struct t_weechat_plugin *plugin,
+          const char *url,
+          struct t_hashtable *options,
+          int timeout,
+          t_hook_callback_url *callback,
+          const void *callback_pointer,
+          void *callback_data)
+{
+    struct t_hook *new_hook;
+    struct t_hook_url *new_hook_url;
+
+    new_hook = NULL;
+    new_hook_url = NULL;
+
+    if (!url || !url[0] || !callback)
+        goto error;
+
+    new_hook = malloc (sizeof (*new_hook));
+    if (!new_hook)
+        goto error;
+
+    new_hook_url = malloc (sizeof (*new_hook_url));
+    if (!new_hook_url)
+        goto error;
+
+    hook_init_data (new_hook, plugin, HOOK_TYPE_URL, HOOK_PRIORITY_DEFAULT,
+                    callback_pointer, callback_data);
+
+    new_hook->hook_data = new_hook_url;
+    new_hook_url->callback = callback;
+    new_hook_url->url = strdup (url);
+    new_hook_url->options = (options) ? hashtable_dup (options) : NULL;
+    new_hook_url->timeout = timeout;
+    new_hook_url->thread_id = 0;
+    new_hook_url->thread_running = 0;
+    new_hook_url->hook_timer = NULL;
+    new_hook_url->output = hashtable_new (32,
+                                          WEECHAT_HASHTABLE_STRING,
+                                          WEECHAT_HASHTABLE_STRING,
+                                          NULL, NULL);
+    hook_add_to_list (new_hook);
+
+    if (weechat_debug_core >= 1)
+    {
+        gui_chat_printf (NULL,
+                         "debug: hook_url: url=\"%s\", "
+                         "options=\"%s\", timeout=%d",
+                         new_hook_url->url,
+                         hashtable_get_string (new_hook_url->options,
+                                               "keys_values"),
+                         new_hook_url->timeout);
+    }
+
+    hook_url_transfer (new_hook);
+
+    return new_hook;
+
+error:
+    if (new_hook)
+        free (new_hook);
+    if (new_hook_url)
+        free (new_hook_url);
+    return NULL;
+}
+
+/*
+ * Frees data in a url hook.
+ */
+
+void
+hook_url_free_data (struct t_hook *hook)
+{
+    if (!hook || !hook->hook_data)
+        return;
+
+    if (HOOK_URL(hook, url))
+    {
+        free (HOOK_URL(hook, url));
+        HOOK_URL(hook, url) = NULL;
+    }
+    if (HOOK_URL(hook, options))
+    {
+        hashtable_free (HOOK_URL(hook, options));
+        HOOK_URL(hook, options) = NULL;
+    }
+    if (HOOK_URL(hook, hook_timer))
+    {
+        unhook (HOOK_URL(hook, hook_timer));
+        HOOK_URL(hook, hook_timer) = NULL;
+    }
+    if (HOOK_URL(hook, thread_running))
+    {
+        pthread_cancel (HOOK_URL(hook, thread_id));
+        HOOK_URL(hook, thread_running) = 0;
+    }
+    if (HOOK_URL(hook, output))
+    {
+        hashtable_free (HOOK_URL(hook, output));
+        HOOK_URL(hook, output) = NULL;
+    }
+
+    free (hook->hook_data);
+    hook->hook_data = NULL;
+}
+
+/*
+ * Adds url hook data in the infolist item.
+ *
+ * Returns:
+ *   1: OK
+ *   0: error
+ */
+
+int
+hook_url_add_to_infolist (struct t_infolist_item *item,
+                          struct t_hook *hook)
+{
+    if (!item || !hook || !hook->hook_data)
+        return 0;
+
+    if (!infolist_new_var_pointer (item, "callback", HOOK_URL(hook, callback)))
+        return 0;
+    if (!infolist_new_var_string (item, "url", HOOK_URL(hook, url)))
+        return 0;
+    if (!infolist_new_var_string (item, "options", hashtable_get_string (HOOK_URL(hook, options), "keys_values")))
+        return 0;
+    if (!infolist_new_var_integer (item, "timeout", (int)(HOOK_URL(hook, timeout))))
+        return 0;
+    if (!infolist_new_var_integer (item, "thread_running", (int)(HOOK_URL(hook, thread_running))))
+        return 0;
+    if (!infolist_new_var_pointer (item, "hook_timer", HOOK_URL(hook, hook_timer)))
+        return 0;
+    if (!infolist_new_var_string (item, "output", hashtable_get_string (HOOK_URL(hook, output), "keys_values")))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Prints url hook data in WeeChat log file (usually for crash dump).
+ */
+
+void
+hook_url_print_log (struct t_hook *hook)
+{
+    if (!hook || !hook->hook_data)
+        return;
+
+    log_printf ("  url data:");
+    log_printf ("    callback. . . . . . . : 0x%lx", HOOK_URL(hook, callback));
+    log_printf ("    url . . . . . . . . . : '%s'", HOOK_URL(hook, url));
+    log_printf ("    options . . . . . . . : 0x%lx (hashtable: '%s')",
+                HOOK_URL(hook, options),
+                hashtable_get_string (HOOK_URL(hook, options),
+                                      "keys_values"));
+    log_printf ("    timeout . . . . . . . : %ld", HOOK_URL(hook, timeout));
+    log_printf ("    thread_running. . . . : %d", (int)HOOK_URL(hook, thread_running));
+    log_printf ("    hook_timer. . . . . . : 0x%lx", HOOK_URL(hook, hook_timer));
+    log_printf ("    output. . . . . . . . : 0x%lx (hashtable: '%s')",
+                HOOK_URL(hook, output),
+                hashtable_get_string (HOOK_URL(hook, output),
+                                      "keys_values"));
+}
diff --git a/src/core/hook/wee-hook-url.h b/src/core/hook/wee-hook-url.h
new file mode 100644
index 000000000..1b306659b
--- /dev/null
+++ b/src/core/hook/wee-hook-url.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2023 Sébastien Helleu <flashcode@flashtux.org>
+ *
+ * This file is part of WeeChat, the extensible chat client.
+ *
+ * WeeChat is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * WeeChat is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with WeeChat.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WEECHAT_HOOK_URL_H
+#define WEECHAT_HOOK_URL_H
+
+struct t_weechat_plugin;
+struct t_infolist_item;
+struct t_hashtable;
+
+#define HOOK_URL(hook, var) (((struct t_hook_url *)hook->hook_data)->var)
+
+typedef int (t_hook_callback_url)(const void *pointer, void *data,
+                                  const char *url,
+                                  struct t_hashtable *options,
+                                  struct t_hashtable *output);
+
+struct t_hook_url
+{
+    t_hook_callback_url *callback;     /* URL callback                      */
+    char *url;                         /* URL                               */
+    struct t_hashtable *options;       /* URL options (see doc)             */
+    long timeout;                      /* timeout (ms) (0 = no timeout)     */
+    pthread_t thread_id;               /* thread id                         */
+    int thread_running;                /* 1 if thread is running            */
+    struct t_hook *hook_timer;         /* timer to check if thread has ended*/
+    struct t_hashtable *output;        /* URL transfer output data          */
+};
+
+extern char *hook_url_get_description (struct t_hook *hook);
+extern struct t_hook *hook_url (struct t_weechat_plugin *plugin,
+                                const char *url,
+                                struct t_hashtable *options,
+                                int timeout,
+                                t_hook_callback_url *callback,
+                                const void *callback_pointer,
+                                void *callback_data);
+extern void hook_url_free_data (struct t_hook *hook);
+extern int hook_url_add_to_infolist (struct t_infolist_item *item,
+                                         struct t_hook *hook);
+extern void hook_url_print_log (struct t_hook *hook);
+
+#endif /* WEECHAT_HOOK_URL_H */
diff --git a/src/core/wee-command.c b/src/core/wee-command.c
index 6269b945c..64fb1ea08 100644
--- a/src/core/wee-command.c
+++ b/src/core/wee-command.c
@@ -63,6 +63,7 @@
 #include "wee-string.h"
 #include "wee-sys.h"
 #include "wee-upgrade.h"
+#include "wee-url.h"
 #include "wee-utf8.h"
 #include "wee-util.h"
 #include "wee-version.h"
@@ -2223,6 +2224,15 @@ COMMAND_CALLBACK(debug)
         return WEECHAT_RC_OK;
     }
 
+    if (string_strcmp (argv[1], "url") == 0)
+    {
+        url_debug ^= 1;
+        gui_chat_printf (NULL,
+                         _("Debug hook_url: %s"),
+                         (url_debug) ? _("enabled") : _("disabled"));
+        return WEECHAT_RC_OK;
+    }
+
     if (string_strcmp (argv[1], "windows") == 0)
     {
         debug_windows_tree ();
@@ -7056,14 +7066,17 @@ COMMAND_CALLBACK(upgrade)
     }
 
     /*
-     * it is forbidden to upgrade while there are some background process
-     * (hook type "process" or "connect")
+     * it is forbidden to upgrade while there are some background process or
+     * thread (hook types: process, connect, url)
      */
-    if (weechat_hooks[HOOK_TYPE_PROCESS] || weechat_hooks[HOOK_TYPE_CONNECT])
+    if (weechat_hooks[HOOK_TYPE_PROCESS]
+        || weechat_hooks[HOOK_TYPE_CONNECT]
+        || weechat_hooks[HOOK_TYPE_URL])
     {
         gui_chat_printf (NULL,
                          _("%sCan't upgrade: there is one or more background "
-                           "process (hook type 'process' or 'connect')"),
+                           "process/thread running (hook type: process, "
+                           "connect or url)"),
                          gui_chat_prefix[GUI_CHAT_PREFIX_ERROR]);
         return WEECHAT_RC_OK;
     }
@@ -8189,7 +8202,7 @@ command_init ()
            " || set <plugin> <level>"
            " || dump|hooks [<plugin>]"
            " || buffer|certs|color|dirs|infolists|libs|memory|tags|"
-           "term|windows"
+           "term|url|windows"
            " || callbacks <duration>[<unit>]"
            " || mouse|cursor [verbose]"
            " || hdata [free]"
@@ -8227,6 +8240,7 @@ command_init ()
            "    mouse: toggle debug for mouse\n"
            "     tags: display tags for lines\n"
            "     term: display infos about terminal\n"
+           "      url: toggle debug for calls to hook_url (display output hashtable)\n"
            "  windows: display windows tree\n"
            "     time: measure time to execute a command or to send text to "
            "the current buffer\n"
@@ -8256,6 +8270,7 @@ command_init ()
         " || mouse verbose"
         " || tags"
         " || term"
+        " || url"
         " || windows"
         " || time %(commands:/)"
         " || unicode",
diff --git a/src/core/wee-hook.c b/src/core/wee-hook.c
index b6bf36d96..758052a72 100644
--- a/src/core/wee-hook.c
+++ b/src/core/wee-hook.c
@@ -46,7 +46,7 @@
 char *hook_type_string[HOOK_NUM_TYPES] =
 { "command", "command_run", "timer", "fd", "process", "connect", "line",
   "print", "signal", "hsignal", "config", "completion", "modifier",
-  "info", "info_hashtable", "infolist", "hdata", "focus" };
+  "info", "info_hashtable", "infolist", "hdata", "focus", "url" };
 struct t_hook *weechat_hooks[HOOK_NUM_TYPES];     /* list of hooks          */
 struct t_hook *last_weechat_hook[HOOK_NUM_TYPES]; /* last hook              */
 int hooks_count[HOOK_NUM_TYPES];                  /* number of hooks        */
@@ -59,50 +59,98 @@ int hook_socketpair_ok = 0;            /* 1 if socketpair() is OK           */
 /* hook callbacks */
 t_callback_hook *hook_callback_add[HOOK_NUM_TYPES] =
 { NULL, NULL, NULL, &hook_fd_add_cb, NULL, NULL, NULL, NULL, NULL, NULL,
-  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
 t_callback_hook *hook_callback_remove[HOOK_NUM_TYPES] =
 { NULL, NULL, NULL, &hook_fd_remove_cb, NULL, NULL, NULL, NULL, NULL, NULL,
-  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
 t_callback_hook *hook_callback_free_data[HOOK_NUM_TYPES] =
-{ &hook_command_free_data, &hook_command_run_free_data,
-  &hook_timer_free_data, &hook_fd_free_data,
-  &hook_process_free_data, &hook_connect_free_data,
-  &hook_line_free_data, &hook_print_free_data,
-  &hook_signal_free_data, &hook_hsignal_free_data,
-  &hook_config_free_data, &hook_completion_free_data,
-  &hook_modifier_free_data, &hook_info_free_data,
-  &hook_info_hashtable_free_data, &hook_infolist_free_data,
-  &hook_hdata_free_data, &hook_focus_free_data };
+{
+    &hook_command_free_data,
+    &hook_command_run_free_data,
+    &hook_timer_free_data,
+    &hook_fd_free_data,
+    &hook_process_free_data,
+    &hook_connect_free_data,
+    &hook_line_free_data,
+    &hook_print_free_data,
+    &hook_signal_free_data,
+    &hook_hsignal_free_data,
+    &hook_config_free_data,
+    &hook_completion_free_data,
+    &hook_modifier_free_data,
+    &hook_info_free_data,
+    &hook_info_hashtable_free_data,
+    &hook_infolist_free_data,
+    &hook_hdata_free_data,
+    &hook_focus_free_data,
+    &hook_url_free_data,
+};
 t_callback_hook_get_desc *hook_callback_get_desc[HOOK_NUM_TYPES] =
-{ &hook_command_get_description, &hook_command_run_get_description,
-  &hook_timer_get_description, &hook_fd_get_description,
-  &hook_process_get_description, &hook_connect_get_description,
-  &hook_line_get_description, &hook_print_get_description,
-  &hook_signal_get_description, &hook_hsignal_get_description,
-  &hook_config_get_description, &hook_completion_get_description,
-  &hook_modifier_get_description, &hook_info_get_description,
-  &hook_info_hashtable_get_description, &hook_infolist_get_description,
-  &hook_hdata_get_description, &hook_focus_get_description };
+{
+    &hook_command_get_description,
+    &hook_command_run_get_description,
+    &hook_timer_get_description,
+    &hook_fd_get_description,
+    &hook_process_get_description,
+    &hook_connect_get_description,
+    &hook_line_get_description,
+    &hook_print_get_description,
+    &hook_signal_get_description,
+    &hook_hsignal_get_description,
+    &hook_config_get_description,
+    &hook_completion_get_description,
+    &hook_modifier_get_description,
+    &hook_info_get_description,
+    &hook_info_hashtable_get_description,
+    &hook_infolist_get_description,
+    &hook_hdata_get_description,
+    &hook_focus_get_description,
+    &hook_url_get_description,
+};
 t_callback_hook_infolist *hook_callback_add_to_infolist[HOOK_NUM_TYPES] =
-{ &hook_command_add_to_infolist, &hook_command_run_add_to_infolist,
-  &hook_timer_add_to_infolist, &hook_fd_add_to_infolist,
-  &hook_process_add_to_infolist, &hook_connect_add_to_infolist,
-  &hook_line_add_to_infolist, &hook_print_add_to_infolist,
-  &hook_signal_add_to_infolist, &hook_hsignal_add_to_infolist,
-  &hook_config_add_to_infolist, &hook_completion_add_to_infolist,
-  &hook_modifier_add_to_infolist, &hook_info_add_to_infolist,
-  &hook_info_hashtable_add_to_infolist, &hook_infolist_add_to_infolist,
-  &hook_hdata_add_to_infolist, &hook_focus_add_to_infolist };
+{
+    &hook_command_add_to_infolist,
+    &hook_command_run_add_to_infolist,
+    &hook_timer_add_to_infolist,
+    &hook_fd_add_to_infolist,
+    &hook_process_add_to_infolist,
+    &hook_connect_add_to_infolist,
+    &hook_line_add_to_infolist,
+    &hook_print_add_to_infolist,
+    &hook_signal_add_to_infolist,
+    &hook_hsignal_add_to_infolist,
+    &hook_config_add_to_infolist,
+    &hook_completion_add_to_infolist,
+    &hook_modifier_add_to_infolist,
+    &hook_info_add_to_infolist,
+    &hook_info_hashtable_add_to_infolist,
+    &hook_infolist_add_to_infolist,
+    &hook_hdata_add_to_infolist,
+    &hook_focus_add_to_infolist,
+    &hook_url_add_to_infolist,
+};
 t_callback_hook *hook_callback_print_log[HOOK_NUM_TYPES] =
-{ &hook_command_print_log, &hook_command_run_print_log,
-  &hook_timer_print_log, &hook_fd_print_log,
-  &hook_process_print_log, &hook_connect_print_log,
-  &hook_line_print_log, &hook_print_print_log,
-  &hook_signal_print_log, &hook_hsignal_print_log,
-  &hook_config_print_log, &hook_completion_print_log,
-  &hook_modifier_print_log, &hook_info_print_log,
-  &hook_info_hashtable_print_log, &hook_infolist_print_log,
-  &hook_hdata_print_log, &hook_focus_print_log };
+{
+    &hook_command_print_log,
+    &hook_command_run_print_log,
+    &hook_timer_print_log,
+    &hook_fd_print_log,
+    &hook_process_print_log,
+    &hook_connect_print_log,
+    &hook_line_print_log,
+    &hook_print_print_log,
+    &hook_signal_print_log,
+    &hook_hsignal_print_log,
+    &hook_config_print_log,
+    &hook_completion_print_log,
+    &hook_modifier_print_log,
+    &hook_info_print_log,
+    &hook_info_hashtable_print_log,
+    &hook_infolist_print_log,
+    &hook_hdata_print_log,
+    &hook_focus_print_log,
+    &hook_url_print_log,
+};
 
 
 /*
diff --git a/src/core/wee-hook.h b/src/core/wee-hook.h
index 04b17c921..bebb0419e 100644
--- a/src/core/wee-hook.h
+++ b/src/core/wee-hook.h
@@ -40,6 +40,7 @@ struct t_hook;
 #include "hook/wee-hook-process.h"
 #include "hook/wee-hook-signal.h"
 #include "hook/wee-hook-timer.h"
+#include "hook/wee-hook-url.h"
 
 struct t_gui_bar;
 struct t_gui_buffer;
@@ -73,6 +74,7 @@ enum t_hook_type
     HOOK_TYPE_INFOLIST,                /* get some info as infolist         */
     HOOK_TYPE_HDATA,                   /* get hdata pointer                 */
     HOOK_TYPE_FOCUS,                   /* focus event (mouse/key)           */
+    HOOK_TYPE_URL,                     /* URL transfer                      */
     /* number of hook types */
     HOOK_NUM_TYPES,
 };
diff --git a/src/core/wee-url.c b/src/core/wee-url.c
index 2c6be1f4f..7ec89b94f 100644
--- a/src/core/wee-url.c
+++ b/src/core/wee-url.c
@@ -44,6 +44,7 @@
     { #__name, CURLOPT_##__name, URL_TYPE_##__type, __constants }
 
 
+int url_debug = 0;
 char *url_type_string[] = { "string", "long", "long long", "mask", "list" };
 
 /*
@@ -1013,8 +1014,6 @@ struct t_url_option url_options[] =
     { NULL, 0, 0, NULL },
 };
 
-char url_error[CURL_ERROR_SIZE + 1];
-
 
 /*
  * Searches for a constant in array of constants.
@@ -1116,7 +1115,7 @@ weeurl_search_option (const char *name)
  */
 
 size_t
-weeurl_read (void *buffer, size_t size, size_t nmemb, void *stream)
+weeurl_read_stream (void *buffer, size_t size, size_t nmemb, void *stream)
 {
     return (stream) ? fread (buffer, size, nmemb, stream) : 0;
 }
@@ -1126,12 +1125,27 @@ weeurl_read (void *buffer, size_t size, size_t nmemb, void *stream)
  */
 
 size_t
-weeurl_write (void *buffer, size_t size, size_t nmemb, void *stream)
+weeurl_write_stream (void *buffer, size_t size, size_t nmemb, void *stream)
 {
     return (stream) ? fwrite (buffer, size, nmemb, stream) : 0;
 }
 
 /*
+ * Adds data to a dynamic string (callback called to catch stdout).
+ */
+
+size_t
+weeurl_write_string (void *buffer, size_t size, size_t nmemb, void *string)
+{
+    if (!string)
+        return 0;
+
+    string_dyn_concat ((char **)string, buffer, size * nmemb);
+
+    return size * nmemb;
+}
+
+/*
  * Sets option in CURL easy handle (callback called for each option in hashtable
  * "options").
  */
@@ -1303,6 +1317,17 @@ weeurl_set_proxy (CURL *curl, struct t_proxy *proxy)
 /*
  * Downloads URL using options.
  *
+ * If output is not NULL, it must be a hashtable with keys and values of type
+ * "string". The following keys may be added in the hashtable,
+ * depending on the success or error of the URL transfer:
+ *
+ *   key           | description
+ *   --------------|--------------------------------------------------------
+ *   response_code | HTTP response code (as string)
+ *   headers       | HTTP headers in response
+ *   output        | stdout (set only if "file_out" was not set in options)
+ *   error         | error message (set only in case of error)
+ *
  * Returns:
  *   0: OK
  *   1: invalid URL
@@ -1312,20 +1337,28 @@ weeurl_set_proxy (CURL *curl, struct t_proxy *proxy)
  */
 
 int
-weeurl_download (const char *url, struct t_hashtable *options)
+weeurl_download (const char *url, struct t_hashtable *options,
+                 struct t_hashtable *output)
 {
     CURL *curl;
     struct t_url_file url_file[2];
     char *url_file_option[2] = { "file_in", "file_out" };
     char *url_file_mode[2] = { "rb", "wb" };
+    char url_error[CURL_ERROR_SIZE + 1], **string_headers, **string_output;
+    char str_response_code[32];
     CURLoption url_file_opt_func[2] = { CURLOPT_READFUNCTION, CURLOPT_WRITEFUNCTION };
     CURLoption url_file_opt_data[2] = { CURLOPT_READDATA, CURLOPT_WRITEDATA };
-    void *url_file_opt_cb[2] = { &weeurl_read, &weeurl_write };
+    void *url_file_opt_cb[2] = { &weeurl_read_stream, &weeurl_write_stream };
     struct t_proxy *ptr_proxy;
-    int rc, curl_rc, i;
+    int rc, curl_rc, i, output_to_file;
+    long response_code;
 
     rc = 0;
 
+    string_headers = NULL;
+    string_output = NULL;
+    url_error[0] = '\0';
+
     for (i = 0; i < 2; i++)
     {
         url_file[i].filename = NULL;
@@ -1334,6 +1367,7 @@ weeurl_download (const char *url, struct t_hashtable *options)
 
     if (!url || !url[0])
     {
+        snprintf (url_error, sizeof (url_error), "%s", _("invalid URL"));
         rc = 1;
         goto end;
     }
@@ -1341,6 +1375,7 @@ weeurl_download (const char *url, struct t_hashtable *options)
     curl = curl_easy_init ();
     if (!curl)
     {
+        snprintf (url_error, sizeof (url_error), "%s", _("not enough memory"));
         rc = 3;
         goto end;
     }
@@ -1358,7 +1393,19 @@ weeurl_download (const char *url, struct t_hashtable *options)
             weeurl_set_proxy (curl, ptr_proxy);
     }
 
+    /* set callback to retrieve HTTP headers */
+    if (output)
+    {
+        string_headers = string_dyn_alloc (1024);
+        if (string_headers)
+        {
+            curl_easy_setopt (curl, CURLOPT_HEADERFUNCTION, &weeurl_write_string);
+            curl_easy_setopt (curl, CURLOPT_HEADERDATA, string_headers);
+        }
+    }
+
     /* set file in/out from options in hashtable */
+    output_to_file = 0;
     if (options)
     {
         for (i = 0; i < 2; i++)
@@ -1369,15 +1416,33 @@ weeurl_download (const char *url, struct t_hashtable *options)
                 url_file[i].stream = fopen (url_file[i].filename, url_file_mode[i]);
                 if (!url_file[i].stream)
                 {
+                    snprintf (url_error, sizeof (url_error),
+                              (i == 0) ?
+                              _("file \"%s\" not found") :
+                              _("can not write file \"%s\""),
+                              url_file[i].filename);
                     rc = 4;
                     goto end;
                 }
                 curl_easy_setopt (curl, url_file_opt_func[i], url_file_opt_cb[i]);
                 curl_easy_setopt (curl, url_file_opt_data[i], url_file[i].stream);
+                if (i == 1)
+                    output_to_file = 1;
             }
         }
     }
 
+    /* redirect stdout if no filename was given (via key "file_out") */
+    if (output && !output_to_file)
+    {
+        string_output = string_dyn_alloc (1024);
+        if (string_output)
+        {
+            curl_easy_setopt (curl, CURLOPT_WRITEFUNCTION, &weeurl_write_string);
+            curl_easy_setopt (curl, CURLOPT_WRITEDATA, string_output);
+        }
+    }
+
     /* set other options in hashtable */
     hashtable_map (options, &weeurl_option_map_cb, curl);
 
@@ -1386,11 +1451,36 @@ weeurl_download (const char *url, struct t_hashtable *options)
 
     /* perform action! */
     curl_rc = curl_easy_perform (curl);
-    if (curl_rc != CURLE_OK)
+    if (curl_rc == CURLE_OK)
+    {
+        if (output)
+        {
+            curl_easy_getinfo (curl, CURLINFO_RESPONSE_CODE, &response_code);
+            snprintf (str_response_code, sizeof (str_response_code),
+                      "%ld", response_code);
+            hashtable_set (output, "response_code", str_response_code);
+        }
+    }
+    else
     {
-        fprintf (stderr,
-                 _("curl error %d (%s) (URL: \"%s\")\n"),
-                 curl_rc, url_error, url);
+        if (output)
+        {
+            if (!url_error[0])
+            {
+                snprintf (url_error, sizeof (url_error),
+                          "%s", _("transfer error"));
+            }
+        }
+        else
+        {
+            /*
+             * URL transfer done in a forked process: display error on stderr,
+             * which will be sent to the hook_process callback
+             */
+            fprintf (stderr,
+                     _("curl error %d (%s) (URL: \"%s\")\n"),
+                     curl_rc, url_error, url);
+        }
         rc = 2;
     }
 
@@ -1403,6 +1493,21 @@ end:
         if (url_file[i].stream)
             fclose (url_file[i].stream);
     }
+    if (output)
+    {
+        if (string_headers)
+        {
+            hashtable_set (output, "headers", *string_headers);
+            string_dyn_free (string_headers, 1);
+        }
+        if (string_output)
+        {
+            hashtable_set (output, "output", *string_output);
+            string_dyn_free (string_output, 1);
+        }
+        if (url_error[0])
+            hashtable_set (output, "error", url_error);
+    }
     return rc;
 }
 
diff --git a/src/core/wee-url.h b/src/core/wee-url.h
index a70e29842..cfa8f6f00 100644
--- a/src/core/wee-url.h
+++ b/src/core/wee-url.h
@@ -54,10 +54,12 @@ struct t_url_file
     FILE *stream;                      /* file stream                       */
 };
 
+extern int url_debug;
 extern char *url_type_string[];
 extern struct t_url_option url_options[];
 
-extern int weeurl_download (const char *url, struct t_hashtable *options);
+extern int weeurl_download (const char *url, struct t_hashtable *options,
+                            struct t_hashtable *output);
 extern int weeurl_option_add_to_infolist (struct t_infolist *infolist,
                                           struct t_url_option *option);